The Pokémon with this Ability takes double damage from Hex and Wake-Up Slap; can be affected by Dream Eater, Nightmare, and Bad Dreams; and cannot successfully use Rest. However, due to not actually having the sleep status condition, the Pokémon with this Ability is not considered to have a status condition for the purposes of effects such as Purify and Chesto Berries.

If a Pokémon that already has a status condition gains Comatose (i.e. due to Transform or Imposter), it will not be cured of its status condition. If the Pokémon was asleep, the status has its normal effect, unaffected by Comatose.